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From: josef@nixdorf.de (Moellers)
Newsgroups: comp.protocols.iso
Subject: Re: Question on Layer1-Layer2 Interface
Message-ID: <josef.657792050@peun11>
Date: 5 Nov 90 08:00:50 GMT
References: <josef.657189877@peun11> <ENAG.90Nov1075351@hild.ifi.uio.no>
Sender: news@nixpbe.nixdorf.de
Lines: 68

In <ENAG.90Nov1075351@hild.ifi.uio.no> enag@ifi.uio.no (Erik Naggum) writes:

>In article <josef.657189877@peun11> josef@nixdorf.de (Moellers) writes:

>   Questions:
>   1. Is this dialing part of ISO layer 1 (physical layer)?
>      In my opinion, it is.

>In my opinion, it's part of a primitive Network Layer.

I know that connection establishment is part of the Network Layer, but ...
My main problem is with the signals on the control lines, like CTS, RTS,
DSR, DTR, RI, ...).
If you look at said (draft) standard ISO/DIS 10022 it only specifies a
	PhC-ACTIVATE request
with "Parameters associated with the classes of service (see clause 8)
are for further study", and "Clause 8" mentioning
a) Type of transmission: synchronous and asynchronous
b) Mode of operation: duplex, half-duplex, and simplex.
   [ Stuff left out here ]
c) Topology: point-to-point and multi-endpoint.

To get back to my examples: V.25bis or X.25:
During connection establishment, both have states of the control lines
that are distinct from the state of the control lines during data
transfer. E.g. V.25 bis specifies that during the dialling phase
(V.25bis calls this "DTE-DCE dialogue" and "Call establishment")
	DTR=ON	DSR=OFF
	RTS=ON	RI=OFF
Whereas during data transfer
	DTR=ON	DSR=ON	<<<!
	RTS=X	RI=OFF

>   2. How do I specify the address/numbers to use?

>Have you tried a sequence of digits?  :-)

>Seriously, being part of the Network Layer, I would guess you could
>construct some Network Service Access Point address which would
>conveniently map to the telephone number.

>Note: By putting connection establishment into the Network Layer, you
>can use different Data Link protocols for connection establishment and
>release than for data transfer, since you talk to the modem.

>I'm almost of the opinion that you could construct a whole seven-layer
>model for dialling and phone protocols.  They did it with Digital
>Subscriber Signalling system # 1 and Signalling System # 7, yet I
>routinely view the dialling and the phone connection as pretty
>low-level.

My question stays as it is:
ISO/DIS 10022 specifies that in order to activate a PhC (Physical
Connection), one has to send a PhC-ACTIVATE request to the Layer-1
Module. From the DIS, I would depict this as (example):
    <PhC-ACTIVATE, asynchronous, duplex, point-to-point>
But this doesn't specify what "number to dial".
My idea would be something like (example):
    <PhC-ACTIVATE, asyncronous, duplex, point-to-point, ":0049=1234=56789;9999">
for a V.25bis Modem.

If I am wasting bandwidth on this rather trivial matter, sorry!

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